To me quitting implies that you gave up on something, that it becomes too difficult, and you are scared to fail, so you quit. But I think that the opposite of a "completer" is a "fragmenter" if you will. I don't quit things, I AM NOT a quitter, and you will never, ever hear me speak of something being too hard and giving up. I will not admit to that, being a quitter, because I am not a quitter.
In case you didn't catch that I will remind you again, I AM NOT A QUITTER!
I merely, fragment. I start things that I don't finish. I tend to put too much on my plate. I am a habitual multi-tasker. And women, I know most of you nag on your boyfriends, husbands, male friends, co-workers, and family members that they are unable to do more than one thing at a time (I do it too, I'm not laying blame, I'm guilty), but they aren't inefficient, we are CURSED. It is a curse to be able to multi-task. If I could shut down the parts of my brain that are used to multi-task I would get a lot more done, and I would consider myself more of a completer.
But besides that, I think my problem is that I become disinterested. I get bored with my projects and move on to the next thing. I usually come to the conclusion that it's not worth my time. But it had to be worth my time at some point for me to start the project, right?
Like this blog for instance, I want to stay on top of it. I want to blog at least once a week. When I have profound (and not so profound) thoughts about my journey to be a better person I want to write them down and document them. But if i don't do it right then and there I forget, and then the once profound (or not) thought, feeling, experience I had goes missing, lost, forever forgotten in the hodge-podge of miscellaneous memories in my psyche. So I say, well it must not be worth my time, or energy if I can't find the time to put forth the effort... But it is. I'm not quitting. I will finish what I started.
If it was worth my time once, it will remain worth my time until I the project is completed. Finish what you start.